Chapter 9. The Marking of the Righteous and the Slaying of the Wicked.
In this chapter we see God's dealings with Jerusalem through heavenly visitants whose activities are reproduced on earth. Nebuchadnezzar would think that he was in charge of events, but Ezekiel, and the people he spoke to, would know that it was Yahweh Who was in charge, and that Nebuchadnezzar was only His instrument. However before that the righteous had to be protected by being marked as God's by an angel of mercy. This would then be followed in vision by the sending forth of the Destroyers, and, in the following chapter, by the city being showered with the burning coals of judgment and destruction.
The chapter reminds us of the Angel of Death at the Exodus (chapter 12) and the destroying Angel of Yahweh in 2Sa 24:16-17; 1 Chronicles 21:15-27. See also 2 Chronicles 32:21; Isaiah 37:36; Amos 9:1. While refined the idea was not new.